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Electric Current
by Ron Kurtus (updated 30 May 2023)
Electric current is the movement or flow of electrically charged particles around an electric circuit, often in a metal wire. Those particles are usually electrons, although there are some situations where the current consists of positive charged (+) ions in an electrolyte material.
The SI unit of electric current is the ampere (A).
The flow of charged particles may be in one direction, such as in direct current (DC) electricity or alternating directions as in alternating current (AC) electricity.
By convention, electric current moves from the positive terminal to the negative. However, the flow of electrons is from negative to positive.
Questions you may have include:
- What is the definition of an ampere?
- What is the convention for current flow?
- What is the convention for flow of electrons?
This lesson will answer those questions. Useful tool: Units Conversion
Ampere is unit of current
The ampere (A) is the standard unit of electric current. It is a measure of the rate that electric charges pass a given point in an electric circuit per second.
One ampere equals 6.241*1018 electrons passing a point per second or one coulomb per second. (The coulomb (C) is the SI unit of electric charge.)
(See Basic Units of Electric Circuits for more information.)
Current Flow Convention
The convention is that current is the flow of electric charges around a circuit from the positive source terminal to the negative.
This was the convention chosen during the discovery of electricity in which the direction of electric current was thought to flow in a circuit.
(See Direction of Direct Current (DC) Electricity for more information)
Electron Current Flow
The flow of electrons around the circuit is opposite to the direction of the conventional current flow and is negative to positive. For example, the electrons flow from the negative pole of the battery (the cathode) and return back to the positive pole (the anode) of the battery.
This is because the charge on an electron is negative by definition and so is attracted to the positive terminal. This flow of electrons is called Electron Current Flow.
Summary
Electric current is the movement or flow of electrically charged particles around an electric circuit.
The SI unit of electric current is the ampere (A).
By convention, electric current moves from the positive terminal to the negative. However, the flow of electrons is from negative to positive.
Try to do your best
Resources and references
Websites
Electric current - Wikipedia
DC and AC Electricity Resources
Books
(Notice: The School for Champions may earn commissions from book purchases)
Teach Yourself Electricity and Electronics by Stan Gibilisco; McGraw-Hill; (2001) $34.95 - Guide for professionals, hobbyists and technicians desiring to learn AC and DC circuits
Students and researchers
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electric_current.htm
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Electric Current